Apparatus for dispensing a predetermined quantity of fluid



June 25, 1963 H. WILLSHAW 3,095,125

APPARATUS FOR DISPENSING A PREDETERMINED QUANTITY OF FLUID Filed July21, 1960 ttes This invention relates to apparatus for dispensing apredetermined quantity of fluid, and more particularly to apparatus fordispensing measured quantities of flu-id into machines of the type knownas internal mixing machines, such as are used for mixing rubber withcompounding ingredients.

In the mixing of rubber and like plastic materials in an internal mixingmachine, such as is known as a Banbury machine, it is generallynecessary for a quantity of oil or other fluid to be added to the mix.It is often necessary for the fluid to be added to the mix at aparticular stage of the mixing process and in a relatively short spaceof time. In order to add the fluid quickly to the mix it has beenproposed to use a storage tank, connected to the internal mixing machinevia a valve. A measured quantity of fluid is placed in the storage tank,and the tank is pressurised by connecting it to a source ofhigh-pressure compressed air. At the appropriate time in the mixingprocess the valve is opened and the fluid is blown into the mixingmachine by the compressed air.

A disadvantage of the above apparatus is that, in operation, it isdifiicult to prevent the compressed air from following the fluid intothe mixer. If this should occur, there is a danger that some of thefluid together with some of the compounding ingredients, such as carbonblack, may be blown out of the mixer by the compressed air.

According to the invention, apparatus for dispensing a predeterminedquantity of fluid comprises a cylinder having a closed end, the cylinderbeing provided with an inlet valve and an outlet valve, a pistonslidable within the cylinder in fluid-tight engagement therewith, meansfor supplying a predetermined quantity of fluid to the cylinder throughthe inlet valve, a connection for applying pressure to the piston .toeject the measured quantity of fluid through the outlet valve, and meansfor opening and closing the outlet valve.

In a preferred form of the invention an internal mixing machine isprovided with apparatus for dispensing a predetermined quantity of fluidas defined in the preceding paragraph. ,i

Preferably the means for supplying a predetermined quantity of fluid tothe cylinder comprises a tank having a liquid supply valve for allowinga predetermined quantity of liquid to be fed to the tank, a fluid supplyvalve for connection to a source of fluid pressure and an outlet forconnection to said cylinder inlet valve. The predetermined quantity ofliquid may be measured in terms of either volume or weight.

Preferably also, the cylinder is fluid-tightly sealed at its end remotefrom the outlet valve, and the connection comprises a valve, connectedto the cylinder at the end remote from the outlet valve, for connectionto a source of fluid pressure.

One embodiment of the invention will now be described, by way ofexample, with reference to the accompanying drawings in which:

FIGURE 1 is a diagrammatic sketch, partly in cross- 3,fl95,l25 PatentedJune 25, 1963 section, showing the general arrangement of apparatus fordispensing liquid to an external mixing machine;

FIGURE 2 is a cross-sectional side view of part of the apparatus shownin FIGURE 1.

A rigid steel cylinder 1, having its ends closed by steel end plates 2and 3, is connected by means of an axially extending steel pipe 4,fluid-tightly attached to the end plate 3, to the mixing chamber 5 of anexternal mixing machine. The pipe 4 is fluid-tightly attached at its end4a to the wall 6 of the mixing chamber 5 and carries, at the end 4a, arotary plate outlet valve 7 for alternatively allowing communicationbetween the cylinder 1 and the chamber 5 of the mixing machine or forsealing said chamber 5 from said cylinder 1.

The rotary plate outlet valve 7 is operable by means of a rod 8 attachedto the outlet valve 7 at one end, passing axially through the cylinder1, and rotatably supported in a bearing 9 at the centre of the end plate2, the bearing 9 being provided with a fluid-tight gland 10. The end 8aof the rod 8 extends beyond the end plate 2 and is provided with ahalf-coupling 11a connected to a second half-coupling 11b attached to ashaft 12 supported coaxially with the rod 8 in bearings 13 and 14carried in a framework 15 attached to the end plate 2 of the cylinder 1by pillars 16. A pinion 17 is attached to the shaft 12. The pinion 17 isengaged by a rack 18 operatively attached to the piston of adouble-acting pneumatic cylinder and piston assembly 19 mounted with itsaxis at right angles to the shaft 12 on the framework 15.

The cylinder 1 is provided with a steel piston 20 which is slida-ble influid-tight engagement with the walls of the cylinder 1 and with the rod8. The piston 20 is provided with an axial extension 21 for projecting,when the piston is at the end of the cylinder adjacent to the mixingmachine, into the pipe 4, and is of such dimensions as to leave only asmall clearance 'between its outer surface and the inner surface of thesaid pipe when in this position'. tween the piston 20 and the rod 8 byscrew-threaded bushes 24 and 25 respectively, are provided fluid-tightlyto seal the piston to the rod and sealing rings 26 and 27 are providedfluid-tightly to seal the piston to the cylinder 1. s

The end plate 2 of the cylinder -1 is provided with a pipe '28 (seeFIGURE 1) for connection to a compressed air line 29, through a 4-Waysolenoid-operated valve 39' which is also connected via pipes 31 and 32to actuate the double-acting pneumatic cylinder and piston 19. Anonreturn inlet valve 33 is mounted on the end plate 3 to allow liquidto pass into the cylinder and for preventing liquid from escapingtherefrom The cylinder is provided with a jacket 34 (see FIGURE 2)containing electrical heating coils (not shown) to maintain liquidcontained in the cylinder at a suitable temperature to enable it to flowfreely.

A storage tank 35 is provided with an outlet tap 36 connected by a pipe37 to the non-return inlet valve 33 to allow liquid to be fed from thetank into the cylinder. The storage tank 35 is also provided with aninlet 38 having a tap 39 and a non-return liquid supply valve 41 so thata measured quantity of liquid may be poured into the tank 35 from aweighing machine (not shown). The inlet tap 39 may be closed, and thespace in the tank 35 above the liquid to be conveyed to the cylinder mayalternatively be pressurized or connected to atmosphere by means of apipe 41 connected to a 3-way solenoid-operated fluid pressure supplyvalve 42. The fluid pressure supply valve42 is connected to a compressedair line 43 and to atmosphere via pipe 44. The storage tank 35 isSealing rings 22 and 25, held in compression be-- provided withelectrical heating coils (not shown) around its outer surface, and thepipe 37 is lagged.

The operation of the apparatus described above is as follows:

A weighed quantity of liquid is allowed to flow into the storage tank35, the outlet tap 36 being closed and the 3-way fluid pressure supplyvalve 42 being in a position allowing communication between the interiorof the tank 35 and atmosphere. The inlet tap 39 is then closed and the3-way fluid pressure supply v-alve 42 is operated to connect the storagetank to thecompressed air line 43.

When it is desired to charge the cylinder :1 with liquid, the 4-waysolenoid-operated valve 30 is operated to 'open the pipe 28 toatmosphere, the rotary plate outlet valve 7 being in the closedposition. The outlet tap 36 on the storage tank 35 is then opened. Thepressure in the storage tank drives the liquid through the non-returninlet valve 33 into the cylinder and forces the piston 20 towards theend of the cylinder remote from the mixing chamber 5.

When it is desired to inject the liquid in the cylinder into the mixingmachine, the 4-way solenoid valve 30 is operated to admit air pressurethrough the pipe 28 to the space between the piston 20 and the end plate2. The solenoid valve 30 also applies pressure via the pipe 32 to causethe pneumatic cylinder and piston 19 to operate the rack 18 and pinion17 to turn the axially extending rod 8 and thus the rotary plate outletvalve 7, to open the outlet valve 7 to allow the liquid to be injectedino the mixing chamber 5. During this operation, the non-return inletvalve 33 is automatically closed by the liquid pressure, and the axialextension 21 to the piston 20 projects into the pipe 4 connecting thecylinder 1 to themixing machine to ensure that only a negligibleproportion of the liquid remains in the pipe 4 after the injectionoperation. After injection of the liquid into the mixing chamber 5, the4-way solenoid-operated valve 30 is operated to connect the pipes 28 and32 to atmosphere and to apply air pressure via pipe 31 to return thepiston of the pneumatic cylinder and piston to its previous position,thus causing the rotary plate valve to close. I

The measurement of the quantity of liquid to be injected mayalternatively be made by use of the following apparatus (see FIGURE 2);

A limit switch 45 is fixed to the end plate 2 of the cylinder 1 to beoperated by a spring-loaded plunger 46, the end 46:: of the plunger 46being arranged to be contacted and forwd towards the switch 45 by thepiston 20 when a desired quantity of liquid has been admitted to thecylinder.. 7

The limit switch 45 may be connected to means for operating the tap 36to cut off the intake of liquid when a predetermined volume of liquidhas been taken into the cylinder. The quantity of liquid taken into thecylinder in this case is determined by the position of the piston whenthe limit switch operates, and this position may be adjusted by, forexample, varying the length of the plunger 46.

The apparatus according to the invention has the advantage, when used inconjunction with an internal mixing machine, that no air is allowed toenter the mixing chamber of the mixing machine. It provides a quick andaccurate method of injecting measured quantities of liquid into themixer.

A further advantage of the apparatus according to the invention is thatit is particularly suitable for use in fully automatic mixing systems,e.g. systems controlled by cycle controllers, punched cards or tape.

Having now described my invention-what I claim is:

1. Apparatus for injecting a measured amount of material into a mixingchamber comprising, a cylinder having at a delivery end an inlet formaterial and a delivery extension of smaller diameter than that of saidcylinder having one end open to said cylinder and extending from saiddelivery end axially of said cylinder and having at its other end anoutlet to deliver material to the mixing d chamber, a piston in saidcylinder slidable fluid-tightly therein axially toward and from saiddelivery end, an extension of said piston extending axially of andtoward said delivery extension and positioned to extend into saiddelivery extension towards the outlet thereof when said piston movesforwardly towards said delivery end of said cylinder on a forwarddelivery stroke of said piston, said piston extension beingwithdrawnclear of said delivery extension and into said cylinder to permit freeflow of material from said cylinder into said delivery extension on thereturn stroke of said piston, an outlet valve on the outlet of saiddelivery extension to close said outlet, fluid actuated means to openand close said outlet valve and means to admit pressure fluid to theopposite end of said cylinder and simultaneously to said fluid actuatedmeans to open said valve on the forward stroke of said piston andalternatively to exhaust pressure fluid from said opposite end of saidcylinder and to reverse the supply of pressure fluid to said fluidactuated means to close said outlet valve on the return stroke of saidpiston.

2. The apparatus of claim 1 in which said delivery extension and saidextension of said piston are coaxial with said cylinder and piston.

3. Apparatus for injecting fluid material into a mixing chambercomprising, a material feeding cylinder having at a delivery end adelivery extension and an inlet, said delivery extension having an inletend from said cylinder and having at the other end an outletforconnection to a mixing chamber, a supply tank having a delivery conduitto said inlet, a non-return valve in said inlet, a piston slidableaxially in said cylinder and having an extension positioned to extendinto the inlet end of said delivery extension and to be disposed betweenthe inlet end and outlet thereof when said piston is at the limit of aforward movement towards the outlet of said cylinder and to be clear ofsaid inlet to permit free flow of material from said cylinder to saiddelivery extension when said piston is at the limit of its returnstroke, an outlet valve on the outlet of said delivery extension movablein one direction to close said outlet and in the opposite direction toopen said outlet, at fluid actuated means operable in one direction toopen said outlet valve and in the opposite direction to close saidoutlet 'valve and means to deliver pressurized fluid to the end of saidcylinder opposite said delivery end thereof and simultaneously to saidfluid actuated means to open said outlet valve and alternatively to opensaid end of said cylinder to exhaust and to deliver pressurized fluid tosaid fluid actuated means to close said outlet valve.

4. The apparatus of claim 1 in which said outlet valve is a rotary valvehaving a stem extending through said piston and cylinder to said fluidactuated means.

5. The apparatus of claim 4 in which said stem is coaxial with saidpiston and cylinder.

6. The apparatus of claim 4 in which said fluid actuated means comprisesa cylinder and a piston drivably connected to said valve stem to rotatesaid valve-stem and valve in opposite directions to open and close saidvalve.

7. The apparatus of claim 6 comprising a rack drivable by said piston toreciprocate therewith and a pinion mounted on said valve stem andmeshing with said rack.

8. The apparatus of claim 4 in which said means to admit pressure fluidincludes a four-way solenoid operated valve.

9. The apparatus of claim 3 in which said outlet valve is a rotaryvalve.

10. The apparatus of claim 9 in which said rotary,

valve includes an operating stem extending fluid-tightly through saidpiston and the other end of said cylinder to connection with saidoperating means.

11. The apparatus of claim 10 in which said fluid actuated. meanscomprises a valve operating cylinder, a

piston slidable in said cylinder and an actuating means movable by saidpiston to rotate said valve stem.

12. The apparatus of claim 11 in which said actuating means comprises arack driven by said piston and a pinion meshing with said rack and indriving connection with said valve stem.

13. The apparatus of claim 12 in which said means to deliver pressurizedfluid comprises a four-way valve having an inlet, an exhaust outlet, aconnection to one end of said valve operating cylinder and a connectionto the other end of said valve operating cylinder and to the end of saidmaterial feeding cylinder opposite to said extension.

14. The apparatus of claim 13 in which said four-way valve is -asolenoid operated valve and which comprises a limit switch to energizesaid solenoid having an actuating element actuated by the piston of saidmaterial feeding cylinder upon the return stroke of said piston.

References Cited in the file of this patent UNITED STATES PATENTS1,046,781 Hanford Dec. 10, 1912 1,047,492 Bowser Dec. 17, 1912 1,587,912Lip-p et a1. June 8, 1926 1,676,425 Chapman July 10, 1928 1,784,795Skonberg Dec. 9, 1930 2,124,073 Maclean et al. July 19, 1938 2,673,012Harrington Mar. 23, 1954 2,908,424 Illsley Oct. 13, 1959 3,052,379Raspante Sept. 4, 1962

1. APPARATUS FOR INJECTING A MEASURED AMOUNT OF MATERIAL INTO A MIXINGCHAMBER COMPRISING, A CYLINDER HAVING AT A DELIVERY END AN INLET FORMATERIAL AND A DELIVERY EXTENSION OF SMALLER DIAMETER THAN THAT OF SAIDCYLINDER HAVING ONE END OPEN TO SAID CYLINDER AND EXTENDING FROM SAIDDELIVERY END AXIALLY OF SAID CYLINDER AND HAVING AT ITS OTHER END ANOUTLET TO DELIVER MATERIAL TO THE MIXING CHAMBER, A PISTON IN SAIDCYLINDER SLIDABLE FLUID-TIGHTLY THEREIN AXIALLY TOWARD AND FROM SAIDDELIVERY END, AN EXTENSION OF SAID PISTON EXTENDING AXIALLY OF ANDTOWARD SAID DELIVERY EXTENSION AND POSITIONED TO EXTEND INTO SAIDDELIVERY EXTENSION TOWARDS THE OUTLET THEREOF WHEN SAID PISTON MOVESFORWARDLY TOWARDS SAID DELIVERY END OF SAID CYLINDER ON A FORWARDDELIVERY STROKE OF SAID PISTON SAID PISTON EXTENSION BEING WITHDRAWNCLEAR OF SAID DELIVERY EXTENSION AND INTO SAID CYLINDER TO PERMIT FREEFLOW OF MATERIAL FROM SAID CYLINDER INTO SAID DELIVERY EXTENSION ON THERETURN STROKE OF SAID PISTON, AN OUTLET VALVE ON THE OUTLET OF SAIDDELIVERY EXTENSION TO CLOSE SAID OUTLET, FLUID ACTUATED MEANS TO OPENAND CLOSE SAID OUTLET VALVE AND MEANS TO ADMIT PRESSURE FLUID TO THEOPPOSITE END OF SAID CYLINDER AND SIMULTANEOUSLY TO SAID FLUID ACTUATEDMEANS TO OPEN SAID VALVE ON THE FORWARD STROKE OF SAID PISTON ANDALTERNATIVELY TO EXHAUST PRESSURE FLUID FROM SAID OPPOSITE END OF SAIDCYLINDER AND TO REVERSE THE SUPPLY OF PRESSURE FLUID TO SAID FLUIDACTUATED MEANS TO CLOSE SAID OUTLET VALVE ON THE RETURN STROKE OF SAIDPISTON.